Candidates for mayor sparred over the future of Houston during Tuesday night's first and only debate among the seven people vying to run the Bayou City.

It was a two-hour debate but because of its format, there was little back and forth between the two front candidates to compare policy positions. And it was tougher for any one candidate to break through.

Inside the studio of KUHF on the campus of the University of Houston, six candidates faced off. They discussed a lot of normal things, like crime, pension debt and METRO transportation, but a couple odd-ball ideas. Mayor Annise Parker pledged light rails all the way to both Houston airports. Ben Hall told his plans to harvest rain water into drinking water. And one candidate was on stage, advocating an overthrow of the capitalist system.

Polls show this is a race between Hall and Parker, and while Hall was able to put the mayor on the defensive Tuesday night, he was at one point questioned very seriously about his taxes and whether he's paid all he owes.

"My wife and I, Sandra, have paid every penny that we owed to every governmental agency. And in fact, we've paid two-and-a-half times more property taxes in the city of Houston than my neighbor, Ms. Parker," Hall said.

"Ninety-seven percent of Houstonians pay their taxes on time. If you're a school teacher in Spring Branch ISD, you expect to receive your paycheck on time. If more Houstonians followed Mr. Hall's practice, that might not happen," Parker said.

On TV, their ads have gotten ugly toward each other but that was the only time Tuesday night that the two candidates went after each other directly.

Parker agreed to only one televised debate, and only if all her challengers participated in it. Incumbents like that because it diminishes all of her challengers.

By the way, we counted. In the duration of the two-hour debate, Parker was answering questions from reporters for a total of 12 minutes and 18 seconds.